The value of serial prostate specific antigen determinations 5 years after radiotherapy: steeply increasing values...

In 1989 we reported on 124 consecutive unselected patients in whom serial polyclonal prostate specific antigen (PSA) determinations were done after radiotherapy to the prostate for clinical stages A, B, C and D1 disease. After a PSA followup of 32 months 51% of the patients had increasing values, while 41% were stable with a mean PSA level of 2.9 ng./ml. We report an additional followup of 48 months on 113 of those patients, representing a mean overall followup of 6 years. Of the 113 patients 88 (78%) have a precipitously increasing PSA level with median doubling times of 14 (stage A), 15 (stage B), 7 (stage C) and 8 (stage D1) months, respectively, at a mean followup of 5 years after radiotherapy. A total of 23 patients (20%) appears cured with a PSA level of less than 1.7 ng./ml. at a mean followup of 9 years (median 7.7). Of the 113 patients 2 continued to have a decreasing PSA level 3 years after irradiation. Among the cured patients there was no relationship to clinical stage A, B or C cancer. We conclude that approximately 20% of the patients with clinical stages A to D1 prostate cancer can be cured by irradiation therapy. They can be identified by a low PSA level that seems to persist indefinitely. The remaining 80% of the patients in whom radiotherapy fails appear to have an accelerated growth rate suggesting tumor clonogen repopulation during radiotherapy.